My tagged posts don't show up in the Reader's tag searches. I don't think my blog is mature, unless occasional swearing counts. I don't misuse tags and I don't use more than 10 tags and categories. I understand that various things can block my posts from appearing in tags "for a while" but it's frustrating to simply wait "for a while" when I don't know what the problem is, and I don't know how long a "while" is.
Meanwhile, my secondary blog does appear in tags.